[Bug c++/80951] Deducing noexcept only works when also deducing something else

[cvs-commit at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80951

--- Comment #1 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Patrick Palka <ppa...@gcc.gnu.org>:

https://gcc.gnu.org/g:676e987b850a7352ece750a8f3a1ac5dae6b3627

commit r12-7104-g676e987b850a7352ece750a8f3a1ac5dae6b3627
Author: Patrick Palka <ppa...@redhat.com>
Date:   Tue Feb 8 09:11:31 2022 -0500

    c++: deducing only from noexcept-spec [PR80951]

    The "fail-fast" predicate uses_deducible_template_parms used by
    unify_one_argument is neglecting to look inside the noexcept-spec of a
    function type.  This causes deduction to spuriously fail whenever the
    noexcept-spec is the only part of the type which contains a deducible
    template parameter.

            PR c++/80951

    gcc/cp/ChangeLog:

            * pt.cc (uses_deducible_template_parms): Consider the
            noexcept-spec of a function type.

    gcc/testsuite/ChangeLog:

            * g++.dg/cpp1z/noexcept-type25.C: New test.